For koalas, uncontrolled chlamydia can cause blindness and painful cysts in an animal’s reproductive tract that can lead to infertility or even death.
Worse yet, the antibiotics used to treat the disease can destroy the delicate gut flora that needs to consume their staple diet of eucalyptus leaves, leaving some people unable to recover. become. Yet they starve to death.
This disease can also spread rapidly.
In 2008, there was a “very, very low chlamydial prevalence” – about 10% – in the koala population in Gunnedah, a rural town in north-east New South Wales, according to Mark Krockenberger, professor of veterinary pathology at the University of Sydney. . ns
By 2015, this figure had risen to 60%. Now, about 85% of that koala population is infected with the virus, Krockenberger said.
“If you think about it, this is no longer a viable population because of infertility. Every woman infected with chlamydia becomes infertile within a year, maybe a maximum of two years… They don’t breed.” doing it,” she said.
Experts say such conditions in Gunnedah are ongoing among koala populations across Australia, leaving populations already vulnerable to habitat loss due to deteriorating bushfires and deforestation.
Scientists are now testing the chlamydia vaccine for animal safety.
“We run a very high risk, if this vaccine strategy doesn’t work … of local extinction,” Krockenberger said.
Are koalas endangered in Australia?
Few Australian animals are more emblematic than the koala.
The gray, fluffy-eared marsupial, which eats the leaves of eucalyptus trees and carries its young in its pouch, can be found only in Australia and is regularly seen in cultural representations of the country.
But the koala has to face many threats to its existence. In addition to disease, marsupials suffer habitat loss and are often attacked by feral dogs and hit by cars.
But Deborah Tabart, president of the Australian Koala Foundation, says much more needs to be done to protect koalas and their habitat across the country, warning that marsupials could be wiped out within three generations.
“We want a Koala Protection Act,” she said. “If you are really serious about protecting this species you will have legislation that will take effect and that means protecting the trees,” she said.
Campaigners say this would be similar to the Bald Eagle Act in the United States that protects the country’s national emblem from threats to its population and habitat.
How is chlamydia spread?
When faced with threats to the koala’s habitat and food supply, chlamydia can seem like a secondary problem.
But with numbers dwindling, experts said breeding has never been more important.
The Australian cuckoo has two varieties of chlamydia, one of which, chlamydia cattle It is almost entirely responsible for the most severe cases of disease in the population.
The disease is transmitted through social behaviors involving breeding and mating in koala populations, although joeys – baby koalas – can catch the disease from their mothers.
Disease was the second leading cause of death after animal attacks.
Climate change is making the problem worse
The climate crisis has left Australia vulnerable to devastating bushfires, such as those seen in 2019, as well as droughts and heatwaves. This is making the koala more vulnerable to disease.
The Australian government report states that when marsupials are exposed to unusually stressful environmental conditions, including “hot weather, drought, habitat loss and fragmentation”, chlamydia spread more quickly through their populations. Is. Is.
Experts say they have seen rapid outbreaks of a similar disease in the wild. Krockenberger said in his punk sample population, a series of heatwaves and droughts occurred in 2009 and 2010 before the doubling of chlamydia cases.
Peter Timms, professor of microbiology at the University of the Sunshine Coast in Australia, said that once environmental problems cause a koala’s stress hormones to rise, the infection often turns from a relatively minor problem to a “more serious problem”.
Koalas are becoming “stressed over time” by a combination of habitat loss and climate change, he said, weakening their immune systems.
“All of this leads to a poor chlamydia response. It leads them to more severe disease than a low-grade chlamydia infection,” he said.
“That’s what we’re doing with them. And we’re doing it on all fronts.”
Chlamydia vaccine trial for koalas
But help may be on the way for Australia’s koalas.
Timms said control trials are underway to test the vaccine’s effectiveness on small groups of koalas — often about 20 or 30 at a time. The current trial is the largest ever, involving 400 koalas.
Some koalas are vaccinated when brought to an animal hospital with complaints other than chlamydia, while others are given the shot as part of an effort to coexist, he said.
“We know the vaccine can reduce infection rates,” Timms said. “It doesn’t reduce it to zero. There is no vaccine that does, but it does reduce the infection load.”
The process is expected to reduce infection rates, but it is harder to monitor the spread of chlamydia in wild populations, he said.
Krockenberger of the University of Sydney, which is involved in a separate vaccine trial, said the drug is not intended to reverse disease progression in individual koalas. “Once they are chronically infected, they are often able to live reasonably happily, they simply cannot reproduce,” he said.
He said the hope instead is that by reducing the level of infectivity in koalas with chlamydia, researchers will be able to stop the virus from spreading to new hosts and thus maintain breeding populations.
“We also hope that unaffected animals, when they are vaccinated, are more resistant to pick up the infection,” he said.
Tims said that once the vaccine is proven safe and effective, he hopes to roll it out to wildlife hospitals around Australia to vaccinate any koalas that come through their doors.
He said people often ask him how he’s going to vaccinate “the last koala in the last tree” for chlamydia, to which Timms replied that he “isn’t even going to try.” All he can do is try to save as much of the population as possible.
After all, “these are wild animals,” he said.
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